This application requests support for a program of basic and clinical research on Developmental Coordination Disorder (DCD) and sensori-motor learning. The primary objective of this project is to understand how barriers to effective motor learning created by sensori-motor deficits can be overcome to enable children with DCD, and other developmental disorders often co-morbid with DCD, to learn to perform good compliant manual actions and especially, handwriting. The proposed research will involve behavioral studies of sensori-motor learning. Four specific aims will be studied: (1) learning with assistance; (2) generalization from assisted practice and retention; (3) passive versus active practice; and (4) task specific practice. The research findings will provide a much stronger conceptual and theoretical basis for explaining the problems faced by children with DCD and other co-morbid developmental disorders with origins in sensori-motor deficits. The results from this project will also have important direct clinical implications for design of therapeutic training for children with sensori-motor disorders. Furthermore, the results are anticipated to enable future efforts to pursue the developmental effects of sensori-motor deficits on cognitive function and emotional experience.